Hand-held programmer for programmable liquid crystal display

ABSTRACT

A method of writing an electrically writable tag using a hand-held writing device includes the steps of providing an electrically writable tag having a plurality of electrical conductors located on a display surface of the tag, and a mechanical alignment feature including a detent for locating the tag with respect to a hand-held writing device; providing a hand-held writing device having a corresponding plurality of electrical contacts for simultaneously making contact with the electrical conductors of the tag, and a complementary alignment feature with a detent for locating the hand-held writing device with respect to the tag; and locating the hand-held writing device with respect to the tag, using the alignment features, and activating the hand-held writing device to write information on the tag.

FIELD OF THE INVENTION

[0001] The present invention relates to a structure having a flexibledisplay with front electrical contacts to the display.

BACKGROUND OF THE INVENTION

[0002] U.S. Pat. No. 5,751,257 issued May 12, 1998, and U.S. Pat. No.6,253,190 issued Jun. 26, 2001, both to Sutherland show a systemincluding a programmable shelf tag having a bistable liquid crystaldisplay for displaying price data and a Universal Product Code (UPC) barcode, wherein the information programmed in the display remains on thedisplay in the absence of power. The shelf tag has a set ofsynchronizing indicators and corresponding electrical contacts on thefrontside of the display.

[0003] The shelf tag is programmable with a hand-held device that isconnected to a central computer that contains inventory and priceinformation. The hand-held device can be used to scan the synchronizingindicators to identify the location of the electrical contacts andsupplies the electrical contacts with electrical signals to writeappropriate information on the shelf tag. For inventory control andprice updates, the hand-held device is used to first read the UPC barcode on the shelf tag. If a price needs to be updated, the hand-helddevice is then used to write the appropriate price information into thetag. The hand-held device is placed into contact with the shelf tag andis moved across the tag to sequentially make contact with each of thecontacts on the front side of the display. A timing track is included onthe front side of the display. The hand-held device reads the timingtrack optically and synchronizes the signal supplied to the respectivecontacts as the hand-held device is moved across the display. Thedisplay includes an alignment groove and the hand-held device includes aprobe that is located in the alignment groove to position the contactsof the hand-held device relative to the contacts of the display.

[0004] One problem with the system as described by Sutherland is thatincluding the UPC as a writable element on the shelf tag, significantlyincreases the complexity and cost of the shelf tag. The resolutionneeded to produce UPC information requires 113 modules of data, andtherefore requires at least a corresponding number of contacts on thefront of the display.

[0005] Another problem is that the hand-held device must be translatedin a preferred direction (e.g. right to left) and within a preferredtranslation rate to properly program the display. Yet another problem isthat translating the hand-held device across the contacts tends to wearout the contacts of the hand-held device and the shelf tag over time,necessitating replacement or repair of the contacts. A further problemwith the method and apparatus disclosed by Sutherland is that theelectronics of the hand-held device are complicated by the need tosequentially address the contacts of the display.

[0006] There is a need therefore for an improved writable display tagand hand-held programming device that avoids the problems noted above.

SUMMARY OF THE INVENTION

[0007] The need is met according to the present invention by a methodand apparatus that includes an electrically writable tag having aplurality of electrical conductors located on a display surface of thetag, and a mechanical alignment feature including a detent for locatingthe tag with respect to a hand-held writing device; and a hand-heldwriting device having a corresponding plurality of electrical contactsfor simultaneously making contact with the electrical conductors of thetag, and a complementary alignment feature with a detent for locatingthe hand-held writing device with respect to the tag. The hand-heldwriting device is located with respect to the tag, using the alignmentfeatures and activated to write information on the tag.

ADVANTAGES

[0008] The electrically writable tag and writing device of the presentinvention has the advantage that the writing device cooperates with thetag to make precise simultaneous alignment with all of the electricalcontacts of the writable tag.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 shows a front view of a label having a display element usedwith the present invention;

[0010]FIG. 2 is a back view of the label shown in FIG. 1;

[0011]FIG. 3A is a front perspective view of a support body forreceiving the label shown in FIG. 1,

[0012]FIG. 3B is a rear perspective view of the support body of FIG. 3Ashowing placement of an RFID transponder.

[0013]FIG. 4 is a perspective view of the support body with anisotropicconductive tape strips with adhesive backer liner positioned over theconductive strips;

[0014]FIG. 5 is a front view of a completed display tag assembly usedwith the present invention;

[0015]FIG. 6 is a perspective front view of a hand-held writing deviceused with the present invention;

[0016]FIG. 7 is a perspective back view of the hand-held writing deviceshown in FIG. 6;

[0017]FIG. 8 is a partial sectional view of the hand-held writing deviceof FIG. 7 taken along line A-A;

[0018]FIG. 9 is an exploded perspective view of one embodiment of ahand-held writing device according to the present invention; and

[0019]FIG. 10 is a functional block diagram of the hand-held writingdevice.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Referring to FIG. 1, a label 10 includes one or moreelectronically writable display elements 15 constructed by forming aplurality of common conductive character electrodes on a substrate;coating and drying a liquid crystal gelatin dispersion over the commoncharacter electrodes, and printing conductive character elements overthe common character electrodes. The display elements are mounted inwindows 18 cut into a sheet of adhesive print medium having a printablesurface 25. The label is preferably made as shown in U.S. Ser. No.10/134,185 filed Apr. 29, 2002 by Stephenson et al., which isincorporated herein by reference.

[0021] The perforated windows 18 allow character elements 20 on displays15 to be viewed from the front printable side 25 of the label 10.Printable surface 25 allows the addition of static readable informationsuch as bar code and item description to be applied by a printer such asan ink jet printer.

[0022] The reverse side of label 10 shown in FIG. 2 has an adhesivebacking 30 to allow attachment to a support body 35 as well asattachment of the display elements 15 to the back side of the label 10.Display elements 15 are attached to adhesive backing 30 to exposeelectrically conductive pads 22 on the back side of display elements 15.The adhesive backing is covered with a removable liner until the tag isassembled. Prior to assembly, the printable surface 25 has informationprinted on it, for example, by an ink jet printer.

[0023]FIG. 3A shows a front perspective view of a support body 35 havingconductive strips 40 imbedded within it. A recess 45 positions label 10on the support body 35 to form a display tag assembly as shown in FIG.5. Recesses 50 in support body 35 provide clearance for the displayelements 15 to allow the label 10 to lay flat on support body 35.Support body 35 is manufactured, for example, by injection moldingplastic with conductive inserts to provide the conductive strips.Alternatively, the support body can be formed and the conductive stripsapplied subsequently. The display tag assembly may also include an RFID(radio frequency ID) transponder. FIG. 3B is a back view of the supportbody 35 showing a recess 46 for locating the RFID transponder 47 on theback of the support body 35.

[0024] Referring to FIG. 4, electrical connection is provided betweenthe conductive pads 22 on the display elements 15 and the conductivestrips 40 in the support body 35 by anisotropically conductive adhesivestrips 42 having a removable a backer liner 48 (shown partiallyremoved). For assembly, the backer liner of the conductive adhesivestrips 42 is removed, the releasable liner is removed from the back ofthe label 10, and the label 10 is inserted into the recess 45 of thesupport body 35.

[0025]FIG. 5 shows an assembled display tag assembly 55 with a label 10adhered to the support body 35. The character elements 20 on the displayelement 15 show through cut-out windows 18 in the label 10. Theconductive strips 40 are exposed along the bottom edge of the supportbody 35 allowing electrical contacts to be made between a hand-heldwriting device and the display elements 15. The conductive strips 40 inturn contact the conductive pads 22 on the reverse side of the displayelements 15 by way of the anisotropic conductive adhesive 42 thusenabling the state of the character elements 20 to be changed byapplying a suitable electrical signal to the conductive strips 40.

[0026] One element of information, which can be printed on the label, isa UPC bar code 60 Generally, the UPC bar code for a product is staticand does not change for the life of the product. It therefore can bepractically printed on the label 10, as opposed to including it in thewritable display portion of the label. A Universal Product CodeIdentification Number may also be stored in the RFID transponder 47.Other information, such as the designation “price” and “price per unit”is normally printed adjacent the display elements, and a productdescription is normally printed on the label. An image of the productcan also be printed on the label as disclosed in U.S. patent applicationNo. (Stephenson shelf tag with image application), which is incorporatedherein by reference.

[0027] Referring to FIG. 6, a hand-held writing device 68 for writinginformation on the electronically writable display elements 15 includesa standard bar code/RFID transceiver hand-held terminal 65, such as anOpticon Model PHL 2700™ (Opticon Inc., Orangeburg N.Y.) and a shelf tagwriting head 70, which includes a means of precisely locating thewriting head 70 with respect to the support body 35 of theelectronically writable tag 55. The hand-held terminal includes acommunication port 62, such as a standard RS 232 port for communicatingwith a processing and control circuit in the hand-held terminal 65. Thehand-held terminal includes a plurality of operator interface buttons66, a main trigger switch 69, and a display screen 71. The functions ofthe interface buttons and trigger switch, and the information displayedon display screen are all programmable by a user.

[0028] Referring to FIG. 7, the back of the hand-held writing device 68is shown. A plurality of contact pins 75 are arranged in the write head70 to contact the contact strips 40 on support body 35 when the writehead 70 is located over the shelf tag 55. The hand-held terminal 65includes a bar code scanner 92 and an RFID transceiver 93 (shown in FIG.10) having a scanning window 90 located in an opening 85 in the writehead 70 for allowing the scanner to view the bar code 60 on the label10. An alignment feature, such as a precision opening 80 in the writehead 70 is used to locate the write head about the support body 35 toprecisely align the contact pins 75 to the conductive strips 40 onsupport body 35. Detent bumps 98 are molded into the write head 70 andare adapted to snap into recesses 38 (see FIG. 5) in support body 35 toensure proper engagement. The use of an RFID transceiver allows theoption of reading of a Universal Product Code Identification Numberwithout having to precisely aim the hand-held terminal as one has towhen using the bar code scanner feature. Also the RFID transponderallows other programmable information to be stored locally on thedisplay tag assembly 55. The RFID label receives all wirelesscommunication and power from the hand-held terminal.

[0029] An electrical feature, such as an electrical conductor 17 (seeFIG. 1) is provided on the in the display tag assembly 55 that can besensed to determine that the write head is properly aligned with thedisplay tag assembly 55 can also be provided. Sensor pins 95 may beprovided in the write head to make contact with the conductor 17 toprovide feedback to indicate to a user that the write head is properlyaligned with the tag. The indication may be provided via the displayscreen 71. Alternatively, an indicator 120 (see FIG. 6) may be providedon the write head 70. This indicator may emit sound or light to indicatethat proper alignment is achieved.

[0030] Referring to FIG. 8, a partial cross sectional view of thehand-held terminal 65, the write head 70, and the tag 55 shows the writehead 70 located in writing position over electronically writable tag 55.The indicator 120 provides a visual or audible response when sensor pins95 are in contact with the conductor 17 in display tag assembly 55.

[0031] The hand-held writing device 68 can be manufactured as a singleunit, or as shown in FIG. 9 it can comprise a standard commerciallyavailable hand-held terminal 65, and an attachable write head 70. Thewrite head 70 is provided with a circuit board with drive electronics100, power cable 105, communication cable 115, a plurality of contactpins 75, wiring 110 for pins 75, and a mechanical attachment interface72 for releasably attaching the write head 70 to the hand-held terminal65.

[0032] Referring to FIG. 10 the hand-held writing device includes acentral processing and control circuit 130, operator interface 66, 69, adisplay 71, a power supply 125, a bar code scanner 92, an RFIDtransceiver 93, and drive electronics 100 for the write head. For theembodiment where the write head 70 is an attachment to an off the shelfhand-held terminal 65, the location of the components is indicated bydashed lines.

[0033] The invention has been described in detail with particularreference to certain preferred embodiments thereof, but it will beunderstood that variations and modifications can be effected within thespirit and scope of the invention.

Parts List

[0034] PARTS LIST 10 label 15 display element 17 electrical conductor 18perforated window 20 character elements 22 conductive pads 25 printablesurface 30 adhesive backing 35 support body 38 detent recess 40conductive strips 42 conductive adhesive strips 45 recess in supportbody 46 recess in support body 47 RFID transponder 48 backer liner 50display recess 55 display tag assembly 60 UPC printed bar code 62communication port 65 hand-held terminal 66 input buttons 68 hand-heldwriting device 69 main trigger button 70 write head 71 display screen 72mechanical attachment interface 75 contact pins 80 precision opening 85opening for scanner 90 scanning window 92 bar code scanner 93 RFIDtransceiver 95 sensor pins 98 detent bumps 100 circuit board with driveelectronics 105 power cable 110 wiring to pins 115 communications cable120 indicator 125 power supply 130 processing and control circuit

What is claimed is:
 1. A method of writing an electrically writable tagusing a hand-held writing device, comprising the steps of: a) providingan electrically writable tag having a plurality of electrical conductorslocated on a display surface of the tag, and a mechanical alignmentfeature including a detent for locating the tag with respect to ahand-held writing device; b) providing a hand-held writing device havinga corresponding plurality of electrical contacts for simultaneouslymaking contact with the electrical conductors of the tag, and acomplementary alignment feature with a detent for locating the hand-heldwriting device with respect to the tag, and c) locating the hand-heldwriting device with respect to the tag, using the alignment features,and activating the hand-held writing device to write information on thetag.
 2. The method claimed in claim 1, wherein the tag includes anelectrical feature that can be sensed by the hand-held writing devicefor providing an indication that the hand-held writing device is inproper alignment with the conductors of the tag; and the hand-heldwriting device includes a sensor for sensing the electrical alignmentfeature, and an indicator responsive to the sensor for indicating theproper alignment of the hand-held writing device with the tag, andfurther including the step of verifying that the hand-held writingdevice is in proper alignment with the tag before activating thehand-held writing device.
 3. The method claimed in claim 2, wherein theelectrical feature in the tag is a conductor extending across the tagand wherein the sensor in the hand-held device is a spaced apart pair ofcontacts for making electrical contact with the conductor.
 4. The methodclaimed in claim 1, wherein the alignment features are a peripheralframe on the tag and a mating frame on the hand-held writing device. 5.The method claimed in claim 4, wherein the detents are a recess and araised bump on the frames.
 6. The method claimed in claim 1, wherein thetag includes: a) a display element having a single flexible transparentsubstrate, one or more first transparent conductors located on thesubstrate, a layer of polymer dispersed material located over the firstconductor(s), the polymer dispersed material being responsive to anapplied electric field for displaying information and having first andsecond optical states that are both stable in the absence of anelectrical field, one or more second conductors located over the polymerdispersed layer for applying the electric field to the polymer dispersedmaterial between the first and second conductors and a plurality ofdisplay contacts located on the backside of the display for makingelectrical connection to the first and second conductors of the display,and a sheet of adhesive print medium having a die cut label area, anddefining a window in the label area, the display element being mountedsubstrate side down in the window; b) a body having a surface forreceiving the display element, the body defining alignment features forprecisely locating the display element on the surface, contacts on thebody having exposed portions on the surface and located with respect tothe alignment feature for making electrical connection to the first andsecond conductors of the display element and exposed portions thatextend beyond the display element, whereby the first and secondconductors are electrically addressable from the front side of the shelftag label; and c) conductive adhesive located over the exposed portionsof the contacts on the receiving surface.
 7. The method claimed in claim1, wherein the electrically writable tag is a shelf label and theelectrically written displayed information is price.
 8. The methodclaimed in claim 1, further including the step of printing staticinformation on the electrically writable tag.
 9. The method claimed inclaim 8, wherein the static information includes an image of a product.10. The method claimed in claim 8, wherein the static informationincludes information from the group comprising a UPC, a productdescription, and a unit description.
 11. The method claimed in claim 10,wherein the hand-held writing device includes a scanner for reading aUPC on the tag.
 12. The method claimed in claim 1, wherein the tagincludes an RFID transponder, and the hand held-writing device includesan RFID transceiver.
 13. The method claimed in claim 12, wherein theRFID transponder contains a Universal Product Code Identification Numberand the RFID transceiver reads the Universal Product Code IdentificationNumber from the RFID transponder.
 14. A display tag assembly,comprising: a) programmable label, having: i) a display element having asingle flexible transparent substrate, one or more first transparentconductors located on the substrate, a layer of polymer dispersedmaterial located over the first conductor(s), the polymer dispersedmaterial being responsive to an applied electric field for displayinginformation and having first and second optical states that are bothstable in the absence of an electrical field, one or more secondconductors located over the polymer dispersed layer for applying theelectric field to the polymer dispersed material between the first andsecond conductors and a plurality of display contacts located on thebackside of the display for making electrical connection to the firstand second conductors of the display, and ii) a sheet of adhesive printmedium having a die cut label area, and defining a window in the labelarea, the display element being mounted substrate side down in thewindow, and including a releasable backing layer, whereby staticinformation can be printed on the label and the printed label can beremoved from the backing layer and attached to a support having contactsfor making electrical connection to the conductors of the displayelement; and b) a support for receiving the label having: i) a bodyhaving a surface for receiving the label, the body defining a mechanicalalignment feature including a detent for locating the tag with respectto a hand-held writing device; ii) contacts on the body having exposedportions on the surface and located with respect to the alignmentfeature for making electrical connection to the first and secondconductors of the display element and exposed portions that extendbeyond the display element, whereby the first and second conductors areelectrically addressable from the front side of the display tagassembly; iii) conductive adhesive located over the exposed portions ofthe contacts on the receiving surface, and iv) an electrical featurethat can be sensed by the hand-held writing device for providing anindication that the hand-held writing device is in proper alignment withthe conductors of the tag.
 15. The display tag assembly claimed in claim14, wherein the electrical feature in the tag is a conductor extendingacross the tag that is adapted to be contacted by a spaced apart pair ofcontacts in the hand-held device.
 16. The display tag assembly claimedin claim 14, wherein the alignment features are a peripheral frame onthe tag and a mating frame on the hand-held writing device.
 17. Thedisplay tag assembly claimed in claim 14, wherein the detents are arecess and a raised bump on the frames.
 18. The display tag assemblyclaimed in claim 14, wherein the static information is an image of aproduct on the adhesive label.
 19. The display tag assembly claimed inclaim 14, further comprising a second display element mounted in asecond window formed in the adhesive label, and wherein the supportincludes conductors for providing contact to the second display element.20. The display tag assembly claimed in claim 14, wherein the staticinformation includes information from the group comprising a UPC, aproduct description, and a unit description.
 21. The display tagassembly claimed in claim 14, wherein the adhesive print media is inkjetprint paper.
 22. The display tag assembly claimed in claim 14, whereinthe conductive adhesive is an anisotropic adhesive.
 23. The display tagassembly claimed in claim 14, wherein the support further comprises anattachment feature for attaching the support to an existing shelf labelbracket.
 24. The display tag assembly claimed in claim 14, wherein thecontacts are printed circuits on the body.
 25. The display tag assemblyclaimed in claim 14, wherein the body is an injection molded plasticpart and the contacts are conductive plastic molded in the body.
 26. Thedisplay tag assembly claimed in claim 14, wherein the body is aninjection molded plastic part and the contacts are metal conductorsmolded into the body.
 27. The display tag assembly claimed in claim 14,wherein the contacts are a conductive applique.
 28. The display tagclaimed in claim 14, further comprising an RFID transponder that can beprogrammed and sensed by the hand-held writing device.
 29. The displaytag claimed in claim 28, wherein the RFID transponder contains aUniversal Product Code Identification Number.
 30. A hand-held writingdevice for writing information on an electrically writable tag having aplurality of electrical conductors located on a display surface of thetag, and a mechanical alignment feature including a detent for locatingthe tag with respect to a hand-held writing device, comprising: a) ahousing; b) a portable power supply located in the housing; c)processing and control electronics located in the housing and connectedto the power supply; d) an operator interface connected to the controlelectronics; and e) a write head attached to the housing and including acorresponding plurality of electrical contacts connected to the controlelectronics for simultaneously making contact with the electricalconductors of the tag, and a complementary alignment feature with adetent for locating the writing head with respect to the tag.
 31. Thehand-held writing device claimed in claim 30, wherein the tag includesan electrical feature that can be sensed by the hand-held writing devicefor providing an indication that the hand-held writing device is inproper alignment with the conductors of the tag; and wherein thehand-held writing device includes a sensor for sensing the electricalalignment feature and an indicator responsive to the sensor forindicating the proper alignment of the hand-held writing device with thetag.
 32. The hand-held writing device claimed in claim 30, furthercomprising a manually operable trigger for actuating the writing device33. The hand-held writing device claimed in claim 30, further comprisinga display connected to the control electronics for displayinginformation to be written on the tag.
 34. The hand-held writing deviceclaimed in claim 31, wherein the electrical feature in the tag is aconductor extending across the tag and wherein the sensor in thehand-held device is a spaced apart pair of contacts for makingelectrical contact with the conductor.
 35. The hand-held writing deviceclaimed in claim 30, wherein the alignment features are a peripheralframe on the tag and a mating frame on the hand-held writing device. 36.The hand-held writing device claimed in claim 30, wherein the detentsare a recess and a raised bump on the frames.
 37. The hand-held writingdevice claimed in claim 30, further comprising an RFID transceiver forprogramming and reading an RFID transponder in the tag.
 38. The handheld writing device claimed in claim 37, wherein the RFID transpondercontains a Universal Product Code Identification Number and the RFIDtransceiver reads the Universal Product Code Identification Number fromthe RFID transponder
 39. A hand-held writing device for writinginformation on an electrically writable tag having a plurality ofelectrical conductors located on a display surface of the tag, and amechanical alignment feature including a detent for locating the tagwith respect to a hand-held writing device, comprising: a) a hand-heldterminal having a power supply, processing and control electronicsconnected to the power supply, an operator interface connected to thecontrol electronics, a bar code scanner, and a communications port; andb) a write head attached to the hand-held terminal, the write headincluding, i) a corresponding plurality of electrical contacts forsimultaneously making contact with the electrical conductors of the tag,ii) drive electronics connected to the electrical contacts the driveelectronics including a communications port, iii) a power cableconnected between the power supply and the drive electronics and acommunication cable connected between the communication ports in thehand-held terminal and the write head, and iv) a complementary alignmentfeature with a detent for locating the writing head with respect to thetag.
 40. The hand-held writing device claimed in claim 39, wherein thetag includes an electrical feature that can be sensed by the hand-heldwriting device for providing an indication that the hand-held writingdevice is in proper alignment with the conductors of the tag; andwherein the write head includes a sensor for sensing the electricalalignment feature and an indicator responsive to the sensor forindicating the proper alignment of the write head with the tag.
 41. Thehand-held writing device claimed in claim 39, further comprising amanually operable trigger for actuating the writing device.
 42. Thehand-held writing device claimed in claim 39, wherein the hand-heldterminal further comprises a display connected to the controlelectronics for displaying information to be written on the tag.
 43. Thehand-held writing device claimed in claim 39, wherein the electricalfeature in the tag is a conductor extending across the tag and whereinthe sensor in the write head is a spaced apart pair of contacts formaking electrical contact with the conductor.
 44. The hand-held writingdevice claimed in claim 39, wherein the alignment features are aperipheral frame on the tag and a mating frame on the write head. 45.The hand-held writing device claimed in claim 39, wherein the detentsare a recess and a raised bump on the frames.
 46. The hand-held writingdevice claimed in claim 39, an RFID transceiver for programming andreading an RFID transponder on the tag.
 47. The method claimed in claim46, wherein the RFID transponder contains a Universal Product CodeIdentification Number and the RFID transceiver reads the UniversalProduct Code Identification Number from the RFID transponder.
 48. Awrite head for use with a hand-held terminal having a power supply,processing and control electronics connected to the power supply, anoperator interface connected to the control electronics, a bar codescanner, and a communications port, for writing information on anelectrically writable tag having a plurality of electrical conductorslocated on a display surface of the tag, and a mechanical alignmentfeature including a detent for locating the tag with respect to ahand-held writing device, the write head comprising: a) a mechanicalinterface for mechanically attaching the write head to the hand-heldterminal; b) a corresponding plurality of electrical contacts forsimultaneously making contact with the electrical conductors of the tag,c) drive electronics connected to the electrical contacts the driveelectronics including a communications port, d) a power cable for makingelectrical connection between the power supply and the driveelectronics; and e) a communication cable for making electricalconnection between the communication ports in the hand-held terminal andthe write head, and f) a complementary alignment feature with a detentfor locating the writing head with respect to the tag.
 49. The writehead claimed in claim 48, wherein the tag includes an electrical featurethat can be sensed by the hand-held writing device for providing anindication that the hand-held writing device is in proper alignment withthe conductors of the tag; and wherein the write head includes a sensorfor sensing the electrical alignment feature.
 50. The write head claimedin claim 49, further comprising an indicator responsive to the sensorfor indicating the proper alignment of the write head with the tag. 51.The write head claimed in claim 48, wherein the hand-held terminalfurther comprises a display for displaying information to be written onthe tag.
 52. The write head claimed in claim 48, wherein the electricalfeature in the tag is a conductor extending across the tag and whereinthe sensor in the write head is a spaced apart pair of contacts formaking electrical contact with the conductor.
 53. The write head claimedin claim 48, wherein the alignment features are a peripheral frame onthe tag and a mating frame on the write head.
 54. The write head claimedin claim 48, wherein the detents are a recess and a raised bump on theframes.
 55. The write head claimed in claim 48, wherein the bar codescanner in the hand-held terminal includes a scanner opening and whereinthe write head is configured to surround the scanning opening whenattached to the hand-held terminal.
 56. The write head claimed in claim48, where in the mechanical interface comprises a bracket for holdingthe write head to the hand-held terminal.